matt Matt Stock

Matt Stock
CS2310
4/26/2006
Final Report – Testing of Virtual Classroom
Testing is an important an integral part of software engineering, ensuring a quality
product at all levels of production. This is also true of classroom projects like the Virtual
Classroom, where many different people contribute to a single piece of software over the course
of a few years, adding features and dealing with a constantly changing set of requirements.
Testing is important to make sure changes do not breaking existing features, and that the
current set of features being added works properly. The primary task faced for the semester was
testing aspects of the Virtual Classroom, focusing specifically on the Skype element, which was
also added over the course of the multimedia software engineering class.
For proper testing, a proper set of functional requirements should be drawn up before a
single line of code is written for a new feature. These requirements should describe, in detail,
exactly what the new feature will accomplish and how it will function. This is important because
it gives both the developer and the tester a common set of criteria and requirements for the
feature. Though there was no such functional requirements formally drawn up for the Skype
component of the Virtual Classroom, the requirements of how such a component should work is
fairly implicit.
Once a set of requirements exists for a particular feature, it’s possible to draw up a Test
Plan for it and, possibly, the rest of the system. The test plan should cover what is to be tested,
not how the system is to be tested; it should describe the scope of the testing process, give an
overall idea of the approach, what sorts of resources are needed and how they’re allocated, the
procedure for when a bug/defect is found, etc. To aid in the development of a Test Plan, and to
aid overall in documentation for a project, a set of ready-made templates can be used, such as
ReadySetPro. This can help alleviate much of the tedium when it comes to creating software
engineering documentation, addressing issues of formatting and what exactly should be placed in
each document.
From the test plan and the functional requirements, a set of test cases can be written,
testing each part of the new feature specifically and thoroughly. These can be a combination of
unit tests, integration tests, functional tests, and performance tests.
Testing in General
One of the tenets of software testing is that as much of it should be automated as
possible, particularly when following an agile model of development. The Virtual Classroom is
roughly an agile model, in that the set of features and requirements changes from semester to
semester, and new features are always being integrated into the system. This style of
development fosters a test environment that is as automated as possible, particularly with unit
tests. Unit tests are small tests that test one particular aspect of a system, usually independent
of the rest of the system; the idea is that a piece of the system can be isolated and tested
completely on its own. In OOP, this usually means taking a class as a lone entity and testing that
it works properly, isolated from the other objects in the system.
Ideally, when a system uses unit testing, the classes are small enough such that they can
easily be broken apart from each other and tested on their own. It also helps enforce the “one
class, one responsibility” axiom of object-oriented programming. Unit tests, ideally, should be
written before the actual code for the feature is written. The idea is that when all of the tests
pass, the feature works as advertised and development of it is finished; this is hard in practice,
but should be strived for as often as possible.
Test Automation
The idea of test automation is that the tests for the system can be run without any input
at all from a human, and ideally a human doesn’t even have to start the tests. There are many
ways to facilitate this, but the most popular is usually some form of source version control and
“hooks” into the source database.
First, version control allows for all of the source code to be kept in a central repository
which all developers have access to. Changes to the system can then be constantly merged into
the existing source code, without the need for e-mailing of code back and forth or clumsy manual
merging once everyone finishes their task. “Branches” to the source tree can also be made if a
particular feature requires changing a large amount of code, or if a particular task is going to
take a long time.
Second, version control easily allows for automated unit testing whenever a change is
made to the repository. For instance, a hook (or trigger) can be made into the database such
that when a change to the source code is committed, (or about to be committed), a particular
script is run. This script can then run a suite of unit tests that will verify that the changes to the
code do not break the existing system. This ensures that the system is always valid whenever
changes are committed, and keeps the code in the source tree “correct”. (Note: often times, all
of the unit tests take too long to run, so it’s convenient to set up a minimal suite of tests that are
run on commit, and then have the full test suite run overnight automatically).
The Virtual Classroom could certainly benefit from some sort of version control and a
repository. The recommendation is for Subversion (http://subversion.tigris.org), as it’s free and
open source, and provides for “update and commit” semantics rather than “check-out and check-
in” semantics. It also allows for scripts to be run when changes are committed (as well as at
some other points). This would certainly make it easier to develop for the Virtual Classroom, and
it would foster and facilitate a better model of software engineering, rather than the somewhat
“ad-hoc” system that’s currently in place.
Bug Tracking
Along with Subversion, it would be good to run a bug tracker such as Trac
(http://www.edgewall.com/trac/), which would allow bugs to be logged and tracked over the
course of the Virtual Classroom project (and across semesters). A particular benefit of Trac is
that it’s designed to interface natively with Subversion, meaning everything could be integrated
on a single web server for the Virtual Classroom.